Optimization and modeling of photocatalytic degradation of Direct Blue 71 from contaminated water by TiO2 nanoparticles: Response surface methodology approach (RSM)

In the current survey, the removal of dye from contaminated water was studied by photocatalytic degradation using TiO lt;sub gt;2 lt;/sub gt; nanoparticles with respect to pH, TiO lt;sub gt;2 lt;/sub gt; dosage, reaction time, temperature and initial dye concentration. TiO lt;sub gt;2 lt;/sub gt; nanoparticles were investigated by XRD, FESEM and FTIR.The RSM was chosen to study the composition effects of input independent factors and one dependent output response (removal efficiency). The Pvalue (2.2 × 10 lt;sup gt;−16 lt;/sup gt;), Fvalue (1832), R lt;sup gt;2 lt;/sup gt; (multiple Rsquared: 0.9985, adjusted Rsquared: 0.9972), and lack of fit (0.432) indicate that the reduced full second order model is highly significant for dye removal by TiO lt;sub gt;2 lt;/sub gt; nanoparticles.The maximum percentage removal of dye, 90.2%, was achieved at optimum operating conditions including pH=6.5, TiO lt;sub gt;2 lt;/sub gt; dose (1.2 g L lt;sup gt;1 lt;/sup gt;), contact time (67.5 min), temperature ( ), and dye concentrations (55 mg L lt;sup gt;1 lt;/sup gt;)), respectively.The maximum removal efficiency was calculated to be 100%, using regression coefficients derived from the model and the Solver “Addins”.The results indicated that the TiO lt;sub gt;2 lt;/sub gt; photocatalyst was very proper for the removal dye from contaminated water, and it had good efficiency in eliminating textile dyes.